 
   (is (= (rightmost-node nil) 
          nil))
-  
+
   (is (= (rightmost-node {:id 1})
          {:id 1}))
 

  (is (= (leftmost-node nil) 
         nil))

  (is (= (leftmost-node {:id 1}) 
         {:id 1}))

  (is (= (leftmost-node {:id 1 :nodes '({:id 2})}) 
         {:id 2}))

         {:id 3}))
  
  (is (= (rightmost-node {:id 1 :nodes '({:id 2 :nodes ({:id 3})})})
         {:id 3}))

  (is (= (rightmost-node {:id 1 :nodes '({:id 2 :nodes ({:id 3})} {:id 4})})
         {:id 4})))

(with-test 
  (def complete-nodes* 
